1. Field of the Invention
The present invention relates to a manufacturing method of the sealing device, and more particularly to a manufacturing method of the sealing device having a metal fitting and an elastic elastomer bake-molded to the metal fitting. The present invention also relates to a sealing device having a metal fitting and an elastic elastomer bake-molded to the metal fitting.
2. Description of the Related Art
FIG. 15 is a partial cross-sectional view of a conventional sealed bearing. As shown in FIG. 15 of a conventional sealing device 51, the sealing device 51 has a metal fitting portion 52 and an elastic elastomer portion 53. The metal fitting portion 52 is like a ring in shape. The metal fitting portion radially outwardly extends from an inner periphery 66 to a curved portion 67, then curves downwardly with curvature. The elastic elastomer portion 53 is also like a ring in shape. The elastomer portion 53 covers the metal fitting portion as shown in FIG. 15. At an outer periphery of the elastomer portion 53 there is a bulge portion 65 which fit into a groove 64 of an outer race 60. At an inner periphery of the elastomer portion 68 there is also a bulge portion having a sealing lip 68, which slidingly contacts with a groove of an inner race 61. Between the outer race 60 and the inner race 61, a bearing (ball bearing or roller bearing) 62 is held. In a space 63 other than bearing, there is a lubricant. The lubricant is sealed by the sealing device 51.
As shown in FIG. 15, in a sealing device 51 or the like for use such as a hard disc drive (HDD) sealing device installed in a small space. the seal 51 is narrow in width. And a metal fitting 52 of the sealing device 51 is also designed as extremely thin as 0.1-0.2 mm in plate thickness as shown in FIG. 15. Accordingly, in case the seal 51 of this type is manufactured by a conventional method, the metal fitting 52 is often displaced from its guide portion 57 (as shown in FIG. 14) due to a fluid pressure of a material for molding an elastic elastomer 53 and a heat expansion of the metal fitting 52. thereby sometimes being deformed or sometimes causes damage to the upper and lower vulcanizing mould 54, 55. These drawbacks are derived from shortness in length in the guide portion 57 of the metal fitting 52. Because the thickness of the seal is limited, so the height of the guide portion 57 becomes small.
Still more, it is not easy to set up the metal fitting 52 onto the vulcanizing mould 54 by using a robot arm (not illustrated in the drawing) when mounting this metal fitting 52 on the lower vulcanizing mould 54.
An object of the present invention is to provide a manufacturing method of the sealing device in which a metal fitting can be positioned exactly and firmly in a vulcanizing mould and the metal fitting can be easily carried onto the vulcanizing mould.
An object of the present invention is achieved by the sealing device comprising: a ring shaped metal fitting portion having an inner plain ring portion, a skirt-like portion extending obliquely or radially outwardly from an outer annular periphery of the inner plain ring portion, and an outer ring-like portion extending radially outwardly from the outer periphery of the skirt-like portion; a ring-shaped elastic elastomer mounting on all over the upper surface of the ring-shaped metal fitting portion and further extending radially outwardly, the elastomer having an upper surface being substantially plain and a curving portion curving downwardly at an outer periphery of the elastomer. The thickness of the elastomer in the axis direction at the peripheral outer portion is thinner than that of the adjacent inner portion.
The object of the present invention can be achieved by a manufacturing method of a sealing device which, in a manufacturing method of a sealing device having a metal fitting and an elastic elastomer that is bake-molded to the metal fitting, comprises the steps of:
forming a metal component having a positioning portion for positioning thereof at a predetermined position in a mould, and a metal fitting portion to be used as the metal fitting in the sealing device; positioning the metal component at the predetermined position in the mould; molding an elastic elastomer in the mould to obtain a bake-molded elastic elastomer having the metal fitting portion monolithically; and removing said positioning portion from the metal fitting portion, to obtain the sealing device.
Moreover the manufacturing method of a sealing device of the present invention in which when providing a metal component in which a positioning portion and a metal fitting portion are provided monolithically, the metal component has a half-cutting portion or a step portion for making separation of the positioning portion from the sealing device.
Still more, according to the manufacturing method of a sealing device, the positioning portion has a cross-sectional L-shaped portion connecting annularly or partially to the metal fitting portion.
The L-shaped portion has a cylindrical portion which guides each metal component slidingly on the surface of the mould into the predetermined place of the mould. The L-shaped portion has also a flange portion being connected to the inner or outer periphery of the metal fitting portion. The flange portion is, in later process. preferably used as a portion to be pushed by such as a punching jig, to separate the positioning portion from the metal fitting portion.
In the manufacturing method of a sealing device of the present invention having above-mentioned processes, a positioning portion and a metal fitting portion are formed monolithically when forming a metal component, and this metal component is positioned onto a vulcanizing mould exactly by means of the positioning portion. The metal fitting portion is used as a part of a metal plate of the sealing device. The positioning portion in a later process is to be separated and removed from the metal fitting portion (part), therefore, it is possible to mold its shape to match a purpose as to position the metal fitting portion exactly and firmly in the vulcanizing mould. Accordingly, by mounting the metal fitting on the vulcanizing mould by means of the positioning portion with a shape and a function as above mentioned, it is possible to prevent the metal fitting from displacement from a guide portion of the vulcanizing mould due to a flow pressure of a material to be molded or a heat expansion of the metal component or the like. In addition, since the metal component is provided as a large-sized portion having monolithically the positioning part (portion) and the product part (portion), it is easily possible to carry this metal component by a robot arm or the like onto the vulcanizing mould.
When providing a metal component having a positioning portion and a metal fitting portion are made monolithically. it is desirable that a half cutting portion, a step portion or the like in a specific portion of the metal component is formed at the same time. The thus obtained metal component can be separated exactly and easily at the half cutting portion or the like, in a process of removing the positioning portion from the metal fitting portion.
The object can be achieved by another method. The process comprises: forming a metal sheet having a plurality of metal fitting and a supporting portion supporting the plurality of metal fitting therein, a central hole in each metal fitting and a wedge-cut (or step or half-cut) annular portion at an outer periphery of each metal fitting; positioning the metal sheet on a large size lower mould having a plurality of mould therein; placing a large size upper would corresponding to the large size lower mould; molding an elastic elastomer into each mould to obtain a bake-molded elastic elastomer having the metal fitting; discharging from the large size mould the bake-molded elastic elastomer having the metal fitting connected to the supporting portion by way of a thinned burr made of bake-molded elastic elastomer; and removing the products by cutting the burr. At the half-cut portion the metal fitting is separated exactly and easily from the supporting portion when the large size moulds is closed or when the elastic elastomer is injected into each mould, so that the outer periphery of the metal fitting can be completely covered by elastic elastomer.